The principle of infrared human body thermometer
The overall working concept of the infrared human body thermometer is that the heat radiated by the human body itself generates infrared energy. The automatic thermometer can automatically measure the infrared energy radiated by the human body and convert it into temperature and display it on the display screen. The circuit of the infrared human body thermometer is still relatively complicated. In order to simplify the problem, we use a schematic block diagram to illustrate its working process. Its overall structure consists of an optical structure part, a photodetector part, an amplifier part and a signal processing part. For example, the filter and integrator in the figure below belong to this, and there is also a display output part. The main task of the optical mechanism is to capture the energy of infrared radiation on the surface of the human body, and then focus the energy of the infrared radiation in the photodetector and convert it into an electrical signal. In fact, it is also the thermal infrared sensor in our industrial control field. Because the electrical signal it converts is very weak, it needs an amplifier to amplify it for use by the next-level signal processing circuit. The signal processing circuit mainly filters out some interference signals and adjusts the waveform of the signal, which is generally realized by circuits such as integrators. Finally, the processed signal is converted into a digital circuit through an A/D converter and the human body temperature is displayed through an LCD display. The above is the approximate working process of this instrument.
Features of infrared human body thermometer
I think the main features of this infrared human body temperature measurement handheld instrument are as follows: first, it can measure human body temperature without contact, which is safe and efficient; second, it has high measurement sensitivity and accuracy, generally accurate to 0.1 degrees Celsius. The third is fast response. The time from measurement to collection of human body surface temperature is generally on the millisecond level, and some can reach the subtle level, thousands of times faster than the temperature measurement speed of our traditional thermometers.
The basic theory of infrared thermometry is that when a substance is above absolute zero (-273.15 degrees Celsius), the molecules of the substance undergo thermal motion and radiate infrared rays outward on its surface, which intensifies as the temperature increases.
There is a pyro-release infrared sensor installed in front of the infrared thermometer. When the infrared sensor senses the heat radiated outward by the human body (infrared rays with intensity corresponding to the body temperature), an electrical signal is generated at the output end of the sensor, and then this The electrical signal representing the temperature is amplified and finally transmitted to the display screen where we can see the temperature value.
